Vulcanizing rubber covered wire

ABSTRACT

A method which comprises applying unvulcanized rubber to a continuous metal wire cord and subjecting the coated cord to high-frequency induction heating as the cord is advanced from a cord supply source to a collection station; the heating step vulcanizing the rubber coating to a high degree adjacent the cord and a low degree at the outer surface of the coating.

[ 1 Feb. 15, 1972 United States Patent Greene 2,427,196 9/1947 Cox......117/233X 3,187,071 6/1965 Radziejowski.....................117/233X [541VULCANIZING RUBBER COVERED WIRE [72] Inventor:

Charles W. Greene, Spartanburg, SC. Deering Milliken Research CoSpartanburg, SC.

June 15, 1970 [21] App]. No.: 46,415

Primary Examiner-Leonard H. Gerin rporation,

[73] Assignee:

Attorney-Norman C. Armitage and H. William Petry ABSTRACT [22] Filed:

A method which comprises applying unvulcanized rubber to a continuousmetal wire cord and subjecting the coated cord to high-frequencyinduction heating as the cord is advanced from a cord supply source to acollection station; the heating step vulcanizing the rubber coating to ahigh degree adjacent the cord and a low degree at the outer surface ofthe coating.

6 0 l 7 1 c 8 0 C 4 B 1 4 B [52] US. [51] lnt.Cl. [58] Field of 5Claims, 2 Drawing Figures References Cited UNITED STATES PATENTS2,261,847 11/1941 Dufoureta1...........................117/233 Pnmtnm 15m2 SHEET 1 1F 2 mvzmon c R LE 3 we? E E N E ATTORNEY PAIENTEBFEBIS I9723.642.532

INVENTOR CHARLES W. G REENE dz/gjg NEY VULCANIZING RUBBER COVERED WIREThis invention relates to the vulcanization of rubber coatings on wireand more particularly relates to the vulcanization of such rubbercoatings while retaining the tackiness of the outer surface.

The tire industry recently has developed considerable interest in tireconstructions which include an annular reinforcement belt or breakerstrip about the periphery of the tire between the tread and the carcass.Such belted tires have the advantage of better road stability and longertread life both in radial and bias ply constructions.

It has been proposed to form tire reinforcement belts by winding one ormore continuous length of cord onto a rotating drum while employing areciprocating guide to traverse the drum surface and to lay the cord ina generally zigzag pattern thereon. Examples of such belts are disclosedin US. Pat. Nos. 2,982,327 and 3,422,874. Prior to the displacement ofthe cord on the drum surface, the cord may be coated with unvulcanizedrubber. This coating which is quite tacky facilitates adhesion of thecord to the drum, adhesion'between adjacent cord and also between thecord and the tread and carcass portions of the tire.

When wire cord is used in the formation of tire belts, a number ofproblems are encountered which are not present when other cord materialsare employed. The stiffness of the wire increases the possibility ofadjacent cords cutting through the intermediate rubber coating so thatthe wire cords contact each other and cause damage or breakage resultingin premature failure of the tire. This is a problem particularly at thepoints in the belt where the wires cross each other.

The present invention provides a novel method of forming a rubbercoating on continuous metal wire cord, the rubber having a high degreeof vulcanization adjacent the cord and a low degree of vulcanization atthe outer surface of the coating. The invention also provides a novelendless reinforcement or belt formed with such coated cord.

The method of the present invention comprises applying unvulcanizedrubber to continuous metal wire cord and subjecting the coated cord tohigh-frequency induction heating as the cord is advanced from a cordsupply source to a collection station. The endless reinforcement or beltof the invention comprises continuous metal wire cord having a rubbercoating thereon with a high degree of vulcanization adjacent the cordinterface and a low degree of vulcanization at the outer surface of thecoating.

Preferably, the induction heating of the rubber coated wire cord isaccomplished at a super atmospheric pressure to minimize the possibilityof vaporization adjacent the interface of the rubber and the wire. Thesuper atmospheric pressure employed is desirably between about and 400pounds per square inch gauge pressure.

The high-frequency heating may be accomplished using known sources ofhigh-frequency energy. The heating of the moving coated cord under asuper atmospheric pressure requires that the heating be done in achamber with a suitable seal arrangement to maintain the pressure levelin the chamber without excessive fluid flow rates while at the same timefacilitating passage ofthe coated cord without damage.

The invention will be illustrated further with reference to theaccompanying drawings in which;

FIG. I is a schematic view in perspective of one form of apparatus oftheinvention, and

FIG. 2 is an enlarged fragmentary view partially in section of partofthe apparatus shown in FIG. 1.

As shown in FIG. 1, an extruder 13 has associated therewith a pressurechamber 14 having a fluid inlet 16 for a pressure fluid such ascompressed air and connections 17. A pulley 18 which is driven by motor19 is disposed at the outlet of chamber 14. A winding apparatus 21 forforming an endless reinforcement includes a rotatable winding drum 23and a guide 22 which is mounted for movement on rod 24. Drum 23 and thecord guide 22 are driven by a power source shown as motor 26. Motor 26is drivingly connected through a belt and pulley arrangement 27 to arotatable shaft 28. One end of shaft 28 IS associated with barrel cam 30and the opposite end through a suitable gear train 31 to shaft 32 fordrum 23. A cam follower 33 connected to the cord guide 22 engages agroove 34 in the surface of cam 30. Groove 34 is of such a configurationthat during rotation of the winding drum 23, cord guide 22 reciprocatesacross drum surface transversely to the direction of rotation. As shownin greater detail in FIG. 2 pressure chamber 14 has an induction heatingcoil 36 disposed therein and an outlet 38.

In the operation of the apparatus illustrated in the drawings, metalwire cord 11 from a supply package 12 is drawn through extruder l3 andpressure chamber 14 by pulley l8 driven by motor 19. Within the chamber,the cord moves through induction heating coil 36. The coated cord thenpasses over guide roller 20 to transversing guide 22 which positions thecord on rotating drum 23. Since the guide 22 reciprocates on rod 24transversely of the rotation of the drum, the cord is laid in a zigzagpattern over the surface of the drum. Gear train 31 includes acombination of gears to control the position of the cord on the drumduring each rotation of the drum so that the cord is laid on the surfacein a predetermined position with respect to previously positioned cordlengths. The winding operation is continued until a completereinforcement is produced, that is, the cord spacing and configurationis substantially uniform through out and is in accordance with thepreselected pattern.

The above description and drawings show that the present inventionprovides a novel method for providing a rubber coating on continuousmetal wire cord, which coating has a high degree of vulcanizationadjacent the wire surface and a low degree of vulcanization at the outersurface of the cord. Furthermore, the present invention provides novelapparatus for producing such coated cord and endless reinforcementstherefrom. Moreover, the invention provides novel apparatus forvulcanizing a running rubber coated metal wire cord.

It will be apparent that various modifications and variations may bemade in the method and apparatus described in detail and shown in thedrawings within the scope of the invention, For example, the heatingchamber may be of a different design. Also, the means for transferringthe cord from the heater and positioning it on the drum surface mayemploy other structural elements. In addition, the cord may be subjectedto a multiplicity ofpasses through the pressure chamber using one ormore heating coils. Therefore, the invention is to be limited only bythe following claims.

That which is claimed is:

1. A method which comprises applying unvulcanized rubber to a continuousmetal wire cord and subjecting the coated cord to high frequencyinduction heating as the cord is advanced from a cord supply source to acollection station; said heating step vulcanizing said rubber coating toa high degree adjacent the cord and a low degree at the outer surface ofthe coating.

2. A method according to claim 1 wherein the induction heating isperformed at a super atmospheric pressure.

3. A METHOD according to claim 2 wherein the pressure is between about20 and 400 p.s.i. gauge.

4. A method according to claim 1 wherein the cord after the heating stepis wound on a drum surface in a zigzag pattern to form an endlessreinforcement.

S. A method according to claim 1 wherein the unvulcanized rubber isapplied to the cord by passing the cord through an extruder.

2. A method according to claim 1 wherein the induction heating isperformed at a super atmospheric pressure.
 3. A METHOD according toclaim 2 wherein the pressure is between about 20 and 400 p.s.i. gauge.4. A method according to claim 1 wherein the cord after the heating stepis wound on a drum surface in a zigzag pattern to form an endlessreinforcement.
 5. A method according to claim 1 wherein the unvulcanizedrubber is applied to the cord by passing the cord through an extruder.